User Guide

Understanding iDAT Technology
196 McAfee VirusScan Anti-Virus Software
How does iDAT updating work?
The AutoUpdate utility downloads two types of files when it connects to the
update site you specified:
• .UPD files. These update files contain only the virus definition changes
between one weekly .DAT file release and the .DAT file release from the
week immediately following. The names for these .UPD files consist of the
version number of a .DAT file release—4053, for example—and the version
number of the very next .DAT release in the sequence, or 4054 in this case.
The complete filename for this .UPD file would therefore be 40534054.UPD.
If you updated your .DAT files every week, the AutoUpdate utility would
simply download the weekly file, then install it alone to bring your .DAT
files up to date. If you have not updated your software for three or four
weeks, however, the AutoUpdate utility would need to download a
number of .UPD packages from which it could extract and install all of the
virus definition files it needed to bring your existing .DAT files up to date.
The utility finds the information it needs to determine which packages to
download in the DELTA.INI file.
• DELTA.INI files. These are text files that describe which weekly .UPD files
the AutoUpdate utility needs to bring your .DAT files completely up to
date. The DELTA.INI file consists of entries that list a number of previous
.DAT file versions, along with the corresponding number of weekly .UPD
files it would need to download from a given .DAT file version number in
order to have all of the virus definitions that the current .DAT file release
has. The file entries have the following format:
[Multiple Patch Table]
4053=10
4054=11
4055=12
[Incremental Resolver]
10=40534054.UPD
11=40544055.UPD
12=40554056.UPD
For this example, suppose you have .DAT version 4053 installed on your
computer and the current .DAT file release is version 4056. The
AutoUpdate utility can look in the DELTA.INI file to learn that it needs to
download the 10th, 11th, and 12th .UPD file releases to have all of the virus
definitions that the current .DAT file release does.